Passengers onboard a disabled cruise ship being towed to shore in the Gulf of Mexico told relatives they are using plastic bags to do "their business" and are otherwise trying to make the best of a bad situation by sleeping under the stars instead of in their stuffy, hot cabins.

“Last that I heard, there's some sewage leaking down the walls. And they're still having to use the restroom in showers,” said Lindsey Peterson, an Irving, Texas resident whose parents are among the 3,143 guests stuck aboard the broken down vessel. “And she says the boat smells awful and people are getting sick because of the smell."

The head of Carnival Cruise Lines says his company is working hard to ensure passengers stranded in the Gulf of Mexico are as comfortable as possible while the vessel is towed to port.

On Wednesday the company wrote in a statement that it had reserved more than 1,500 hotel rooms, and prepared charter flights and coaches to accommodate travelers when they arrive in Mobile, Ala. later this week. A third tugboat has been dispatched to help tow Carnival Triumph back to port and passengers have been offered full refunds, discounts of 15 to 25 percent on a future voyage and $500 compensation.

In the meantime, however, passengers who have been baking on a powerless ship since Sunday, continue to complain of poor conditions.

Jimmy Mowlam, 63, said his 37-year-old son, Rob Mowlam, told him by phone Monday night that the lack of ventilation onboard the ship had made it too hot to sleep inside. He said Rob and his new bride -- they got married onboard Saturday -- are among the many passengers who have set up camp on the ocean liner's decks and in its common areas.

"He said up on deck it looks like a shanty town, with sheets, almost like tents, mattresses, anything else they can pull to sleep on," said Mowlam, 63, who is from Warren, in southeast Texas.

His son added that there is no running water, few working toilets and passengers were given plastic bags to "use for their business."

The ship’s crew, Mowlam’s son said, had started giving away free alcohol to passengers raising concerns about what could happen if the drinking got out of hand.

Other passengers have described more dire conditions, including overflowing toilets and limited access to food.

Texas resident Brent Nutt, whose wife is on the cruise ship, said Monday that she told him the "whole boat stinks extremely bad" and some passengers were getting sick and throwing up. Nutt said his wife reported "water and feces all over the floor."

Despite the abundance of complaints about the lack of functioning restrooms, Carnival Cruise Lines President and CEO Gerry Cahill said at a news conference Tuesday in Miami that most public restrooms on the ship are working, as are some bathrooms in guest cabins. He also said there's running water on the ship.

The Triumph left Galveston, Texas, for a four-day cruise last Thursday carrying 3,143 passengers and 1,086 crew members. On Sunday, the ship was about 150 miles off Mexico's Yucatan Peninsula when an engine room fire knocked out its primary power source, crippling its water and plumbing systems and leaving it adrift on only a backup power.

There were no reported injuries caused by the fire, but Carnival spokeswoman Joyce Oliva said Tuesday that a passenger with a pre-existing medical condition was taken off the ship as a precaution.

Everyone else will likely have to remain onboard until the ship reaches Mobile, Ala., which is expected to happen Thursday, weather permitting.

Besides the three tugs, at least two other Carnival cruise ships have been diverted to the Triumph to transport supplies and a 210-foot Coast Guard cutter was at the scene, Coast Guard Petty Officer Richard Brahm said Tuesday.

"If they do need any help, we're there," he said.

Carnival hasn't determined what caused the fire or how it caused the electrical problems that have crippled the ship's water and plumbing systems, said Oliva, the company spokeswoman.

The National Transportation Safety Board announced Tuesday it has opened an investigation into the cause of the fire. The NTSB said the Bahamas Maritime Agency will lead the investigation because the ship carries a Bahamian flag.

The ship was originally going to be towed to the port in Progreso, Mexico, but after currents pushed it northward, a decision was made to take it to Mobile to make it easier for passengers without passports to get home, the company said.

A similar situation occurred on a Carnival cruise ship in November 2010. That vessel was also stranded for three days with 4,500 people aboard after a fire in the engine room. When the passengers disembarked in San Diego they described a nightmarish three days in the Pacific with limited food, power and bathroom access.

Carnival said in a statement that it had canceled the Triumph's next two voyages scheduled to depart Monday and Saturday.

NBC 5's Ben Russell and Associated Press writers Michael Graczyk and Ramit Plushnick-Masti in Houston and David Warren in Dallas contributed to this report.